A blackout is typically associated with "lights on, no one is home" after a night of consuming large quantities of alcohol. So, a Power Outage surpasses a blackout. It is the next level - "lights are off and no one is home".

Person 1: "Oh man, were you blacked out in this picture? Because it looks like lights are on, but no is home".
Person 2: "No dude, the lights weren't even on."
Person 1: "Oh, so you had a Power Outage!"